EP0333488B1 - Electron gun for color-picture tube - Google Patents

Electron gun for color-picture tube Download PDF

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Publication number
EP0333488B1
EP0333488B1 EP89302624A EP89302624A EP0333488B1 EP 0333488 B1 EP0333488 B1 EP 0333488B1 EP 89302624 A EP89302624 A EP 89302624A EP 89302624 A EP89302624 A EP 89302624A EP 0333488 B1 EP0333488 B1 EP 0333488B1
Authority
EP
European Patent Office
Prior art keywords
electron beam
electrode
electron
beam path
electron gun
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP89302624A
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0333488A1 (en
Inventor
Taketoshi C/O Patent Division Shimoma
Shinpei C/O Patent Division Koshigoe
Ryuichi Murai
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Toshiba Corp
Original Assignee
Toshiba Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Toshiba Corp filed Critical Toshiba Corp
Publication of EP0333488A1 publication Critical patent/EP0333488A1/en
Application granted granted Critical
Publication of EP0333488B1 publication Critical patent/EP0333488B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J29/00—Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
    • H01J29/46—Arrangements of electrodes and associated parts for generating or controlling the ray or beam, e.g. electron-optical arrangement
    • H01J29/48—Electron guns
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J29/00—Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
    • H01J29/46—Arrangements of electrodes and associated parts for generating or controlling the ray or beam, e.g. electron-optical arrangement
    • H01J29/48—Electron guns
    • H01J29/50—Electron guns two or more guns in a single vacuum space, e.g. for plural-ray tube
    • H01J29/503—Three or more guns, the axes of which lay in a common plane
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J29/00—Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
    • H01J29/46—Arrangements of electrodes and associated parts for generating or controlling the ray or beam, e.g. electron-optical arrangement
    • H01J29/48—Electron guns
    • H01J29/50—Electron guns two or more guns in a single vacuum space, e.g. for plural-ray tube
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2229/00—Details of cathode ray tubes or electron beam tubes
    • H01J2229/48—Electron guns
    • H01J2229/4834—Electrical arrangements coupled to electrodes, e.g. potentials
    • H01J2229/4837—Electrical arrangements coupled to electrodes, e.g. potentials characterised by the potentials applied
    • H01J2229/4841—Dynamic potentials
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2229/00—Details of cathode ray tubes or electron beam tubes
    • H01J2229/48—Electron guns
    • H01J2229/4844—Electron guns characterised by beam passing apertures or combinations
    • H01J2229/4848—Aperture shape as viewed along beam axis
    • H01J2229/4858—Aperture shape as viewed along beam axis parallelogram
    • H01J2229/4865—Aperture shape as viewed along beam axis parallelogram rectangle
    • H01J2229/4868—Aperture shape as viewed along beam axis parallelogram rectangle with rounded end or ends
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2229/00—Details of cathode ray tubes or electron beam tubes
    • H01J2229/48—Electron guns
    • H01J2229/4844—Electron guns characterised by beam passing apertures or combinations
    • H01J2229/4848—Aperture shape as viewed along beam axis
    • H01J2229/4872—Aperture shape as viewed along beam axis circular

Definitions

  • a normal electron gun for color-picture tube is an inline three-beam type tube.
  • the inline type triple-gun color-picture tube normally provides a deflection yoke, which generates an inhomogeneous magnetic field consisting of a pin-cushion type horizontally deflecting magnetic field as shown in Fig.1(a) and a barrel type vertically deflecting magnetic field as shown in Fig.1(b).
  • the deflection yoke thus allows the three electron beams to self-converge on a fluorescent screen.
  • Fig.1, B1, B2, and B3 respectively denote electron beams emitted from the inline electron gun. Curves show magnetic fields.
  • This type of self-convergence deflection system does not require an additional device for converging the three electron beams such as a dynamic convergence device, which means it is less costly and allows easier convergence control.
  • a dynamic convergence device which means it is less costly and allows easier convergence control.
  • the color-picture tube employing the inline type triple-electron gun greatly contributes to the quality and performance of a color-picture tube.
  • the inhomogeneous magnetic field brings about an adverse effect of lowering resolution on the peripheral part of the screen of the color-picture tube.
  • the adverse effect is more distinguished as the deflection angle increases from 90° to 110°.
  • a beam spot 1 which is located on the center of the screen, is substantially circular, but a beam spot 2, which is located on the pripheral part of the screen, is formed to have an elliptic high brightness core portion 3 extending horizontally and a low brightness halo portion 4 extending vertically.
  • the electron beam spot on the center of the screen is assumed to have a circular form 5 in section as a result of being converged and diverged while the electron beams pass through a low potential region I and a high potential region II of a main lens. That is, a focusing angle ⁇ 2 is assumed to allow the electron beams through a deflection region 6 to be substantially circular.
  • the electron beam 7 receives as a vertical force the vertical force components 10 and 11 serving to over-focus the vertical components of an electron beam. After being deflected, therefore, the electron beam spot section is formed to be an ellipse 13 whose major axis extends horizontally and a halo 12.
  • This system must have an increased crossover diameter so that the electron beam spot diameter on the center of the screen is made larger, resulting in lowering the resolution on the center of the screen.
  • Another system for reducing the deflection distortion is a system providing an asymmetric pre-focusing lens or locating an asymmetric main lens for under-focusing the vertical components of the electron beam (the latter is disclosed in the U.S. Patent No.4086513).
  • the vertical focusing angle ⁇ 1 of the electron beam is smaller than ⁇ 2 assumed when it is formed to be a substantial circle (as shown in Figs.3 and 4).
  • the vertical force components 19 and 20 shown in Fig.6 are made smaller than those 10 and 11 shown in Fig.4, so that the halo portion 21 is made smaller than the halo portion 12.
  • the electron beam spot on the center of the screen is formed to be an ellipse whose major axis extends vertically, which brings about a shortcoming that the resolution on the center of the screen is made lower.
  • the self-convergence color-picture tube employing an inline type triple-gun greatly contributes to the quality and performance of the color-picture tube, but it has a shortcoming that the resolution on the peripheral part of the screen is inferior and, for improving it, the resolution on the center of the screen is forced to be lower.
  • the position of the electric-field correcting members is preferably such that the distance between the electric-field correcting members of the low potential electrode to the baseplate is larger than the distance between those members of the high potential electrode to its baseplate.
  • a thin plate having a plurality of electron beam path holes should be attached on the high potential electrode side of the low potential electrode, because it is possible to promote a lens effect of a small electron lens caused near each electron beam path hole as well as to control the main lens function by changing the form of each electron beam path hole formed on the thin plate.
  • the electron beam path holes may provide electric-field correcting members as raised portions horizontally formed inside of the low potential electrode and the high potential electrode.
  • the equipotential lines extending in the electrodes therefore, serve to vertically offer the focusing effect around the low potential electrode or the divergent effect around the high potential electrode, so that both effects are stressed vertically.
  • the electron beams are properly focused on the fluorescent screen of the color-picture tube through the weak horizontal focusing and divergent effects and strong vertical focusing and divergent effects.
  • the electron beam spot on the center of the screen is formed to be circular.
  • the resolution on the peripheral part of the screen can be improved.
  • Fig.7(a) is a schematic plan section showing an embodiment of an electron gun for a color-picture tube according to the invention
  • Fig.7(b) is a schematic side section showing the above.
  • an electron gun 100 comprises a heater (not shown) inside of itself and three cathodes KR, KG, and KB disposed in a line, a first electrode 110, a second electrode 120, a third electrode 130, a fourth electrode 140, and a convergence cup 150 disposed in the axial direction of the tube.
  • the electron gun 100 is supported and secured by an insulating supporting rod (not shown).
  • the third electrode 130 consists of two cup-like electrodes 131, 132 whose opening ends are mounted to each other, and a thin plate 133 whose thickness is about 0.6 mm.
  • the fourth electrode 140 side of the cup-like electrode 132 is substantially tabular with no burring portion. On this side are formed three substantially circular electron beam path holes 135R, 135G, and 135B, the maximum diameter of which is 6.2 mm.
  • the thin plate 133 On the thin plate 133 are formed three substantially circular electron beam path holes 136R, 136G, and 136B, which are identical to the electron beam path holes 135R, 135G, and 135B of the cup-like electrode 132.
  • electric-field correcting members 160 and 161 respectively consisting of tabular plates whose thickness is about 1.2 mm, length is about 3.0 mm, and width is 19.0 mm.
  • the electric-field correcting members 160 and 161 are located in a horizontal manner to a trajectory surface of each electron beam and as if they pinch the trajectory surface. These members keep an axial distance (L1) of 3.0 mm from the surface containing the electron beam path holes 135R, 135G, and 135B.
  • a fourth electrode 140 consists of two cup-like electrodes 141 and 142 whose opening ends are closely mounted to each other.
  • the third electrode 130 side of the cup-like electrode 141 is substantially tabular with no burring portion.
  • On this fourth electrode 141 are formed substantially circular electron beam path holes 143R, 143G, and 143B which are similar to the electron beam path holes 135R, 135G, and 135B of the cup-like electrode 132.
  • electric-field correcting members 170 and 171 respectively consisting of tabular plates whose thickness is about 1.5 mm, length is about 3.0 mm, and width is 19.0 mm.
  • the electric-field correcting members 170 and 171 are located in a horizontal manner to a trajectory surface of each electron beam and as if they pinch the trajectory surface. These members keep an axial distance (L2) of 2.0 mm from the surface containing the electron beam path holes 143R, 143G, and 143B.
  • the convergence cup 150 side of the cup-like electrode 142 are formed three substantially circular electron beam path holes 144R, 144G, and 144B, respectively, with large diameters.
  • the convergence cup 150 is in contact with these holes.
  • a d.c. voltage of about 150 V and a modulation signal corresponding to an image to be displayed on a screen are applied on the cathodes KR, KG, and KB of the electron gun 100.
  • the first electrode 110 is grounded.
  • a potential of about 600 V is applied to the second electrode 120.
  • a voltage of about 7 KV is applied to the third electrode 130 and a high voltage of about 25 kV is applied to the fourth electrode 140 through the conductive film, the spring 180, and the convergence cup 150.
  • the interval between the second electrode 120 and the third electrode 130 composes a pre-focusing lens for preliminarily focusing an electron beam emitted from the triode.
  • the main lens affords a focusing effect on the third electrode 130 side to which the relatively low voltage is applied and a divergent effect on the fourth electrode 140 side to which the relatively high voltage is applied. Since the electron beam is greatly influenced by the low voltage side effect, at the last stage, the electron beam is focused on the fluorescent screen.
  • the electric field correcting plates 160, 161, 170, and 171 are provided inside of the third electrode 130 and the fourth electrode 140, so that the horizontal curvature for electric field penetration is different from the vertical one near the electron beam path holes 135R, 135G, 135B, 136R, 136G, 136B, 143R, 143G, and 143B.
  • Fig.8(a) is a vertical section showing the equipotential distribution near the main lens
  • Fig.8(b) is a horizontal section showing the above.
  • the vertical equipotential distribution located inside of the cup-like electrodes 132 and 141 is designed so that the central portions of the equipotential lines are projected within the electrode through the effect of the electric-field correcting members 160, 161, 170, and 171. This effect is very large in the cup-like electrode 141 where the distance L2 is short.
  • the horizontal equipotential distribution is designed so that no equipotential lines are projected as shown in Fig.8(a) because of the absence of the horizontal electric field correcting plates.
  • the vertical curvature of the equipotential lines is designed to be larger than the horizontal curvature.
  • the vertical focusing and divergent effects are relatively stronger, and the horizontal focusing and divergent effects are relatively weaker.
  • Figs.9 and 10 conceptually show the function of the main lens.
  • the electron beam is shown by a real line.
  • the vertical focusing effect has a stronger influence over the electron beam as shown in lines F-G and f-g
  • the horizontal focusing effect has a weaker influence over it as shown in lines F-H and f-h.
  • the vertical divergent effect has stronger influence over the electron beam as shown in lines G-I and g-i
  • the horizontal divergent effect has weaker influence over it as shown in lines H-J and h-j.
  • the main lens affords respective functions to the electron beam according to the vertical or horizontal direction.
  • ⁇ v is a focusing angle in the vertical direction
  • ⁇ H is a focusing angle in the horizontal direction.
  • the sectional shape of the electron beam in the deflection region 200 has a smaller vertical diameter than the horizontal one. That is, the electron beam has an elliptic shape in section, the major axis of which extends horizontally.
  • the electron beam spot shape 201 is substantially circular.
  • the electron beam 300 receives small vertical force components 303 and 304 of the forces 301 and 302 afforded by the horizontally deflecting magnetic field when it is deflected, the deflected beam is hardly distorted.
  • the focusing angle ⁇ v in the vertical direction is small.
  • the electron beam spot shape deflected on the peripheral part of the screen is an ellipse 305 with a suppressed halo portion, the major axis of which ellipse extends horizontally.
  • Fig.12 shows another embodiment of an electron gun for a color-picture tube according to this invention.
  • Fig.12(a) is a schematic plan section showing the embodiment
  • Fig.12(b) is a schematic side section showing it.
  • the electron gun 500 shown in Fig.12 is identical to the electron gun 100 shown in Fig.7 except that the thin plate 133 is removed. When employing the electron gun 500, it is possible to obtain the similar effect as when using the electron gun 100.
  • like reference numbers are given to the members common to those shown in Fig.7
  • At least one group of electron beam path holes are selected out of the electron beam path holes formed on the electron lens side of the low potential electrode or the thin plate closely located on the low potential electrode side or those holes formed on the electron lens side of the high potential electrode, and the openings of the selected group of electron lens path holes should consist of the combination of a circular opening 900 and oval ones 901 as shown in Fig.16.
  • the foregoing methods allow the functioning of the asymmetric lens to be optimized, thus making it possible to achieve excellent resolution over the whole screen of the color-picture tube.

Landscapes

  • Video Image Reproduction Devices For Color Tv Systems (AREA)
EP89302624A 1988-03-16 1989-03-16 Electron gun for color-picture tube Expired - Lifetime EP0333488B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP63062994A JP2693470B2 (ja) 1988-03-16 1988-03-16 カラー受像管
JP62994/88 1988-03-16

Publications (2)

Publication Number Publication Date
EP0333488A1 EP0333488A1 (en) 1989-09-20
EP0333488B1 true EP0333488B1 (en) 1993-05-12

Family

ID=13216433

Family Applications (1)

Application Number Title Priority Date Filing Date
EP89302624A Expired - Lifetime EP0333488B1 (en) 1988-03-16 1989-03-16 Electron gun for color-picture tube

Country Status (6)

Country Link
US (1) US5034652A (ko)
EP (1) EP0333488B1 (ko)
JP (1) JP2693470B2 (ko)
KR (1) KR920000913B1 (ko)
CN (1) CN1019925C (ko)
DE (1) DE68906441T2 (ko)

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP3105528B2 (ja) * 1990-09-17 2000-11-06 株式会社日立製作所 電子銃およびその電子銃を備えた陰極線管
CN1042073C (zh) * 1992-11-02 1999-02-10 东芝株式会社 彩色显像管
JPH0729512A (ja) * 1993-05-14 1995-01-31 Toshiba Corp カラー受像管
KR970009210B1 (en) * 1994-01-21 1997-06-07 Lg Electronics Inc Electron gun for color crt
JP3655440B2 (ja) * 1997-08-05 2005-06-02 松下電器産業株式会社 カラー受像管
KR20000009416A (ko) * 1998-07-24 2000-02-15 김영남 인라인형 전자총을 구비하는 칼라음극선관
JP3926953B2 (ja) * 1999-11-25 2007-06-06 株式会社東芝 カラー受像管

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL7400887A (nl) * 1974-01-23 1975-07-25 Philips Nv Kathodestraalbuis.
US4086513A (en) * 1975-03-03 1978-04-25 Rca Corporation Plural gun cathode ray tube having parallel plates adjacent grid apertures
NL8203322A (nl) * 1982-08-25 1984-03-16 Philips Nv Kleurenbeeldbuis.
JPS61188840A (ja) * 1985-02-15 1986-08-22 Sony Corp 電子銃
JPS62274533A (ja) * 1986-05-22 1987-11-28 Nec Corp 電子銃電極構体

Also Published As

Publication number Publication date
US5034652A (en) 1991-07-23
DE68906441D1 (de) 1993-06-17
DE68906441T2 (de) 1993-09-30
KR920000913B1 (ko) 1992-01-31
CN1036104A (zh) 1989-10-04
EP0333488A1 (en) 1989-09-20
JPH01236554A (ja) 1989-09-21
CN1019925C (zh) 1993-02-17
KR890015333A (ko) 1989-10-30
JP2693470B2 (ja) 1997-12-24

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